Isolation and antiviral activity of water-soluble Cynomorium songaricum Rupr. polysaccharides

Abstract

The plant, Cynomorium songaricum Rupr., is used as a traditional medicine in China and Mongolia. In the present study, two new water-soluble polysaccharides isolated from C. songaricum Rupr. were purified by successive Sephadex G-75 and G-50 column chromatographies and then characterized by high resolution NMR and IR spectroscopies. The molecular weights of two polysaccharides were determined by an aqueous GPC to be  = 3.7 × 10⁴ and 1.0 × 10⁴, respectively. In addition, it was found that the polysaccharide with the larger molecular weight was an acidic polysaccharide. It was found that the iodine-starch reaction of both isolated polysaccharides was negative and the methylation analysis gave 2, 4, 6-tri-O-methyl alditol acetate as a main product. NMR and IR measurements and sugar analysis revealed that both polysaccharides had a (1 → 3)-α-d-glucopyranosidic main chain with a small number of branches. After sulfation, the sulfated C. songaricum Rupr. polysaccharides were found to have a potent inhibitory effect on HIV infection of MT-4 cells at a 50% effective concentration of 0.3-0.4 μg/ml, a concentration that has almost the same high activity as standard dextran and curdlan sulfates, EC₅₀ = 0.35 and 0.14 μg/ml, respectively. The 50% cytotoxic concentration was low, CC₅₀>1000 μg/ml. In addition, the interaction between the sulfated polysaccharides and poly-l-lysine as a model protein compound was investigated by a surface plasmon resonance to reveal the anti-HIV mechanism.

Keywords::

• Cynomorium songaricum
• water-soluble polysaccharide
• structure
• NMR
• anti-HIV activity
• SPR

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was partly supported by a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science 2012-2014 [number 24550129].